Case hardening is used on low carbon steels where the choice of alloy determines the properties that can be achieved.
Case hardening is applied to components that are very close to their finished shape.
Carbon is diffused into the surface of the component in the CARBURISATION process.
Either directly after carburisation or after cooling and re-heating the component is rapidly cooled in the quench process.
The quench process transforms the crystal micro structure of the carbon rich surface – the case – to give a hard, wear resistant layer around the tougher, less brittle core.